Some Apple Mac users who rushed to upgrade their systems with the company s latest security patch were left to scramble for help after a conflict with disk encryption software from PGP rendered the upgraded Macs un-bootable. Reports of users who were unable to boot their Macs after upgrading their Mac OS X systems to the 10.6.5 version began appearing in PGP support forums on Wednesday. PGP now a division of Symantec Corp. has not yet responded to a request for comment.
Source: https://threatpost.com/pgp-disk-encryption-bricks-upgraded-macs-111110/74665/